1. Field of the Invention
The present invention relates to an active material for batteries based on carbon-coated lithium sulfide.
2. Discussion of Background Information
Uses for batteries, for example in electric vehicles, or else storage technologies for renewable energies (e.g. wind energy, solar energy, etc.) require the development of new technologies for rechargeable batteries having significantly higher specific energies than have hitherto been available or been able to be procured commercially.
The lithium-sulfur battery is a very promising technology for these fields of application.
Accordingly, attempts have been made in the prior art to provide active materials based on lithium sulfide. Enveloping lithium sulfide with a carbon layer, with the carbon layer being produced from polyacrylonitrile or sucrose, is known from WO 2013/057023.
Furthermore, lithium-based systems which are based not on lithium sulfide but on other lithium compounds have been studied in the prior art. Thus, for example, L. Zhao et al., Adv. Mater. 2011, 23, 1385-1388, discloses enveloping especially Li4Ti5O12 with a carbon layer, with the latter being produced from ionic liquids. The advantageous properties of the shell are ascribed to, inter alia, interphase formation with Ti.
Paraknowitsch et al., Macromol. Chem. Phys. 2012, 213, 1132-1145, also describe various carbon materials obtained from ionic liquids.
It is an object of the present invention to provide active materials for batteries which have improved properties compared to the systems known from the prior art.
Accordingly, it is an object to find, inter glia, an inexpensive, effective and reliable process for producing active materials for batteries, in particular taking into account a future possible industrial use of the process.
Furthermore, it was an object to provide advantageous active materials for batteries, corresponding electrodes and batteries themselves.
In addition, it was an object of the present invention to find corresponding uses for the active materials of the invention.
A further object of the present invention was to provide a cathode material using the active materials of the invention.